The relay switchover from one group setting to the other during the running condition. Overcurrent Relay Technical Reference Manual 3. • Single-line diagram (meter and relay single line or one line diagram) Shows the overall scheme and connections and interactions between equipment and relay system components but in a simplified manner. Since this method involves smoothening, the operation is slow. Numerical Relays working explained in this post with the help of a Numerical relay used in industrial applications. There is normally a single function in the old relays so that lots of equipment are used to protect, control and monitor a substation bay. Utilities are now demanding IEC 61850 capabilities available in any substation related hardware or software. Event record stores inside the relay all the changes taking place in the system like protection element, pick-up, and drop-off operation, output and input energization and setting change, etc. >LED reset NO 2. This adds to savings in wiring material and labour. The electro-mechanical relay operates when operating torque/fence exceeds the restraining torque/force. The digital filter design will The RAM is tested by writing and reading a test pattern. The ability to detect and correct a failure before the protection system has to operate is in contrast to the traditional protection system wherein a relay failure remains undetected until it fails to operate correctly during an event or until the next maintenance test. It is also possible to upload the revised software to the relay at site without sending the relay back to the manufacturer. Modem power system protection devices are built with integrated functions. Protective relay must be isolated from the high-voltage system but require current and voltage quantities proportional to those on the electric supply system. The differential characteristics define the … Adaption #3 – In distance relays, for different system configurations like parallel feeder in, and parallel out and grounded, different settings can be adapted for this condition. Figure 1: Generalized numerical relay structure 1. Adaption #2 – In transformer protection relay, the third slope is called the bias slope limit, which is used to afford greater stability and this can be achieved by monitoring the through fault current. Simplified functional block diagram for a numerical protective relay 3. Electromechanical and static relays have fixed wiring and the setting is manual. Very helpful article. This has helped me enhance my knowledge of protection relays. Hence for complex, reliable, multi-functional requirement numerical relays shall be used. The most important self-diagnostic functions implemented in digital multi-function relays are detailed below. We know that most of the high end industrial application devices have relays for their effective working. Numeric relays are programmable rel… The size of the numerical relays is much less as compared to that of electromechanical and static relays due to the multi-functionality approach of the former. The flash ROM contents are checked by calculating the check-sum and comparing it with the pre-computed and stored check-sum. The voltage and current data are derived using the power system simulator (PSB power system block set for SIMULINK/MATLAB). Not as active as I used to but will use the information from your site to assist when I am visiting my homeland, in addition to local colleges in Ontario. Numerical relays are provided with a metering function and separate panel mounted meters can be eliminated. Traditionally, electromechanical and static protection relays offered single-function, single characteristics, whereas modern numeric protection offers multi-function and multiple characteristics. The multiplexed analogue signal is sampled and converted into digital data using the ADC. This record gives the nature of fault waveforms (transient) and instantaneous values, etc. These scaled signals are filtered by using a low-pass filter to prevent a liasing of the high-frequency components into the fundamental frequency component. P14D Functional Block Diagram • Digital input subsystem. This check-sum is then compared with the calculated check-sum of the set-points stored in the RAM every time a set-point task is executed. Modern numerical relays have other additional functions like: Recommended reading: Mastering switchgear control circuits – AC/DC circuits and circuit breaker closing circuit, Mastering switchgear control circuits – AC/DC circuits and circuit breaker closing circuit. The following cost reduction benefit the consumer: Numerical relays are tested as per IEC 255-5 for dielectric, impulse voltage and insulation resistance. On the other hand, in the modern protection schemes, smart protection relays support more functions in one piece of device. for the control and operation of manufacturing process equipment and machinery. The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. Very useful article, and well written. The PSL imposes no delay on logic throughput, using concurrent processing being used instead of sequential equations and avoiding any logic ‘race’ issues. Adaption #4 – In IDMTL relays, depending upon the system condition like the number of incomers and outgoing feeders, different settings can be selected and better protection can be achieved. As CTs and VTs used for protection functions may have a different accuracy specification than those used for metering functions, such data cannot be sufficiently accurate for tariff purposes. 1: Block Diagram of Numerical Relay Description: The microprocessor based relay works on numbers that quantities value of signal its works on numbers so that’s why it’s known as “Numerical Relay” In which fig CT/PT are used to sense the current and voltage of … Flash memory is used for storing the programme and RAM (random access memory) is used for temporary storage of variables, target information and oscillography. Self-diagnostics is one of the most important features of numerical relays; it was not available in either electromechanical or static relay design. Thus the size of instrument panels is reduced, thereby resulting in further cost reduction. A faster method is phase splitting the wave ... relay has a microprocessor, it lacks the attributes of a digital/numeric relay, and hence the term “microprocessor In simple Inverse definite minimum time lag (IDMTL) overcurrent and earth fault relays, multiple characteristics like NI, VI, El, LTI and DTL characteristics are available in relay and the required characteristics can be selected at site. I seek every opportunity to update my educational and experienced background. The panel space required is very less. The widespread acceptance of numerical technology by the customer and the experiences of the user helped in developing the second generation numerical relays in 1990. The digital protective relay is a protective relay that uses a microprocessor to analyze power system voltages, currents or other process quantities for the purpose of detection of faults in an electric power system or industrial process system. Multiplexer and Analog to digital converter 5. The first protection devices based on microprocessors were employed in 1985. However, it is sufficiently accurate for an operator to assess the system conditions and take appropriate decisions. And the quantizer will sample the output in the form of discrete (step wise). The host processor receives these parameters from the dual-ported memory and per-forms relay logic and other timing functions to generate appropriate trip or alarm output signals. Numerical relays use a specialised digital signal processor (DSP) as the computational hardware, along with associated software tools. Brief Introduction about Relay: RELAY: A Relay is a protection device that senses the fault in the circuit and gives a trip signal to the Circuit Breaker to isolate the faulty circuit. Some protections also offer adaptable characteristics, which dynamically change the protection characteristic under different system conditions by monitoring the input parameters. are required to construct this protective relay.. Also in motor protection relays, additional information pertaining to positive sequence, negative sequence, equivalent current and difference current (between phases) is available. Fig. The pick-up of the relay is obtained by movement of the movable element in the relay. In the numerical relay the analog signals from CT & PT are processed through the series of hardware blocks and finally supplied to the computer/processor in a digital form where the software algorithm processes the digital signal and takes decision about the trip signal. with time stamping. Thus improvements in numerical relays can be upgraded at site without despatching the relay to the manufacturer which reduces the relay downtime. VT/CT supervision. Figure 1 – Block diagram of numerical relay Communication between the processors is provided by the dual-ported memory. These records can also be fed to the harmonic analyzer software to find out the harmonic content in the fault quantities. An iron core is surrounded by a control coil. Connection Diagram Current Input Voltage Input Binary Input Factory Settings: 1. Well written in broken down sections. Pre-Configured Matching Unit, Retrofit solution for Microshield Overcurrent relay (MSOC), Brochure (English - pdf - Leaflet) Pre-Configured Matching Unit, The solution to mitigate risk and save costs on relay upgrades, Flyer (English - pdf - Leaflet) Digital input/Communication module Input Module The Power system operates with analog parameters. The schematic of a generalized numerical relay structure is shown in Figure 1 [4], [5]. The digital signal processor executes a variety of signal processing algorithms to estimate several parameters of the digitized voltage and current signals, and transfers them to dual-ported memory. The primary method of reducing unwanted induced AC voltage is to bypass these voltages to ground with capacitors. The relay provides metering facility, where the operating personnel can view online different parameters and these metering features can be used as a valuable tool during the commissioning period when primary injection is carried out. The check-sum is calculated as the modul-256 sum of all the bytes. The voltage inputs of the relay are scaled down from the nominal voltage to a low level determined by the ADC (analogue-to-digital converter) input range. fault record, event record and waveform record. What is idmt relay: The IDMT relays are protection relays. The number of protective relays and auxiliary relays are reduced. For example, we have the following protections in numerical relays in-built into one relay. Conventional electromechanical and static relays are hard wired relays.Their wiring is fixed, only their setting can be manually changed. The block diagram of the inverse-time overcurrent relay is shown in the figure. The software provided in a numerical relay is commonly organized in a series of tasks operating in real time. The relaying voltage and currents are passed through an isolation transformer. Thus the cost of CT and PT is reduced. Recommended reading: Testing protection IEDs in IEC 61850 based substation automation systems, Testing protection IEDs in IEC 61850 based substation automation systems. A number of extra quantities can be derived from the measured quantities, depending upon the input signals available. Whenever any set-point is changed, the check-sum of the set-points is calculated from the contents of the EEPROM. Self-check feature improves the protection system reliability. Contact inputs and outputs, user inter-face (keyboard and liquid crystal display) and the serial communication ports (RS-232 and RS-485) are interfaced to the host processor. • Digital relay/ Numerical relay consists of functional block diagram • Analog input subsystem. —W^ÞZñtÉç]îí¼>^ß[,ØVp¬ vŠöRC±¶\M5їƒQÖºÌ öTHuhDRî ¹«JXK²+Ÿ©#CR nG³ÃSÒ:‚­tV'O²ƒ%÷ò»å”±ÙM¥Ð2ùæd(pU¬'_çÞþõ@¿Å5 öÏ\Ðs*)ý&º‹YShIëB§*۝b2¨’ù¹qÆp?hyi'FE'ʄL. In a nutshell, in the conventional protection schemes, all primary equipment such as circuit breakers, CT/VTs and power transformers are connected to the secondary system using the hardwires. Waveform record stores the analogue and digital channel values during the relay operation or on demand. Multi-functions like protection, control, monitoring and measuring are available today in numeric power system protection devices. The relay measures the line current of each phase from each of the windings of the transformer. In numerical relay data storage is done in three formats, i.e. It should be suitable for 2 kV dielectric voltage, 5 kV impulse voltage and insulation resistance > than 1000 M-ohms. • A processor along with RAM (data scratch pad), main memory (historical data file) and power supply. The main component is the real time operating system (RTOS) whose function is to ensure that other tasks are executed as and when required on a priority basis. Protection is enhanced due to their complex, multiple protection characteristic. The main components of numerical relay are- Use of the relay The overcurrent relay REJ 523 is intended for selective short-circuit protection in medium voltage distribution networks but can also be used for protection of generators, motors and transformers. Some examples of these adaptions are: Adaption #1 – In motor protection relay, different settings can be adapted for the starting condition and running condition. The filtered signals are multiplexed using an analogue multiplexer and amplified, if needed, by using a programmable gain amplifier. This is perhaps the most obvious and simplest function to implement, as it involves the least additional processor time. However, sensitive settings can be adapted for these protections during the running conditions of the motor. Knowledge is an ocean . The values that the relay must measure to perform its protection function have already been acquired and processed. What Is Numerical Relay. The relay hardware design includes a watchdog timer re-set circuit to take the processor through an orderly re-set should the programme get lost due to hardware/software glitches. Simulink/MATLAB is used to model the distance relay components such as ADC and digital filters. Fault record gives the complete information about the fault, i.e. Input Module 2. The processed data can be accessed through the relay communication port. Other components such as varistors, chokes and ferrite beads, are also applied to suppress surge voltages and EMI. be used only in the Numerical relays. A relay is generally suitable for temperature as per IEC 255-6 for storage at -25°C to +70°C, and for operation at -25°C to +55°C. It is therefore a simple task, The relay hardware and software are continuously monitored by the relay itself, Nowadays all protection relay manufacturers are trying, Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! Memory 4. This relay f~rmerly is located at the Qislributi~n substati~n and The time-graded protection can also be implemented with definite time underimpedance relays. The 3-Ø voltage and current signals are analog in nature. Communication capability makes the numerical protection system more intelligent and pro-vides valuable information to the user. Fig 27.4 shows the functional block diagram of a digital relay. The current inputs to the relay are scaled down from nominal 5/1 A and are converted into equivalent voltages. Modern numerical protection devices have multiple protection elements and this technique makes the cost of the relay comparable with that of electromechanical and static relays (discrete). These may include: The accuracy of the measured values can only be as good as the accuracy of the transducers used (VTs, CTs, A/D converter, etc.). Interoperability between intelligent electronic devices ( IED ) from different manufactures, shows block. Microprocessor environment dielectric, impulse voltage and current signals are multiplexed using an analogue multiplexer and checked warning! Relays.Their wiring is fixed, only their setting can be called a `` numeric protective relay '' ( PSB system. 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